1. Field of the Invention
The present invention relates to a magnetic-head supporting mechanism for a magnetic-disc apparatus, and in particular, to a magnetic-head supporting mechanism that is excellent in impact resistance.
2. Description of the Related Art
It has been reported that when a large impact is applied to a conventional magnetic-disc apparatus in the direction perpendicular to a disc surface, a slider jumps up from the magnetic disc surface, is tilted while floating, and falls from the angle of a slider floating rail to contact and damage the disc surface (IEEE TRANSACTION ON MAGNETICS Vol. 31, No. 6, pp. 3006 to 3008: NOVEMBER, 1995). This article also reports that a xe2x80x9cjump stopxe2x80x9d is effectively provided on the slider in order to reduce the damage to the disc caused by an impact.
In addition, JP-A-8-102159 discloses a mechanism comprising a pin protrusion (a limiter section) on a cover or on a base of a magnetic-disc apparatus wherein if the magnetic-disc apparatus is subjected to an impact to oscillate a suspension having a magnetic head at its free end, the free end of the suspension contacts the pin protrusion and is stopped from being further displaced toward the base or cover.
According to the conventional mechanism, if the slider is subjected to an impact and leaves the disc surface, the jump height is restricted by the jump stop or pin protrusion to a predetermined value or less. An object of this configuration is to reduce the speed or acceleration at which the slider collides against the disc in order to reduce the damage to the slider and disc upon the impact, thereby improving the impact resistance of the magnetic-disc apparatus.
On the other hand, the degree of damage depends on the magnitude of the speed and acceleration at which the slider contacts the disc as well as the extent of the contact area. That is, the contact area significantly varies depending on whether a floating surface (a surface that is opposed to the disc surface and on which a floating force is effected) of the slider contacts the disc surface in parallel or the slider rotates and contacts the disc surface at the corners of its floating surface or at its bleed surface (a surface that is opposed to the disc surface and on which a floating force is not effected). Thus, even if the slider contacts the disc surface at the same speed and acceleration, the contact area pressure (stress) significantly varies depending on the contact areas of the slider and disc surface, that is, the position of the slider in which it collides against the disc surface, resulting in significantly different degrees of damage. The prior art does not take this point into account.
In view of this point, it is an object of this invention that when the magnetic-disc apparatus is subjected to a large impact to cause the slider to jump from the disc surface and the slider then re-contacts the disc surface, the contacting position of the slider is controlled to prevent the contact area from being reduced in order to reduce contact damage, thereby improving the impact resistance.
In other words, when the magnetic-disc apparatus is subjected to an impact to cause the slider to jump and the slider then re-contacts the disc surface, the position (angle and state) of the slider is controlled to provide a sufficient contact area (prevent the contact area from being reduced) in order to reduce the contact area pressure (stress), that is, damage.
It is another object of this invention to improve the impact resistance of the magnetic-disc apparatus and to provide a magnetic-head supporting mechanism that allows the slider to be easily mounted on the suspension and that has an excellent assembly capability.
To achieve these objects, the magnetic-head supporting mechanism according to this invention is composed of a slider on which a magnetic head is mounted; and a suspension that holds the slider and that presses the slider against the disc surface from the rear surface of the slider (the surface opposite to the disc-opposed surface), the suspension consisting of a gimbal (also referred to as a xe2x80x9cflexurexe2x80x9d) and a load beam.
The gimbal is composed of a mounting portion on which the slider is mounted (normally, joined with an adhesive); a stage portion that connects to one end of the mounting portion; two flexible finger portions extending along the respective sides of the mounting portion from the other end of the stage portion; and a joint portion that connects to the other end of the flexible finger portions to join the load beam and that is joined with the tip of the load beam (normally by means of spot welding).
The gimbal has a low rigidity sufficient to avoid restraining the movement of the slider in the out-of-plane direction perpendicular to the floating surface of the slider, (perpendicular to the floating surface) while having a high rigidity in the in-plane direction (parallel to the floating surface).
The load beam consists of an arm mounting portion, a spring portion, and a flange portion, and the joint portion of the gimbal is joined with the tip of the flange portion. On the other hand, the other end of the flange portion connects to the spring portion, and the other end of the spring portion connects to the arm mounting portion that is mounted on an arm portion that is very rigid. A load generated in the spring portion is transmitted through the flange portion, via a pivot (a protrusion) provided at the tip of the flange portion to protrude in the slider direction, to the mounting portion of the gimbal mounted on the rear surface of the slider. Since the mounting portion is joined with the rear surface of the slider, the load transmitted to the mounting portion acts to press the slider. The load generated in the spring portion is generated by bending the spring through a predetermined angle prior to installation in the magnetic-disc apparatus so that the spring is installed approximately in parallel to the disc surface.
The slider is mounted on the load beam via the gimbal, as described above, and is pivotally supported by the pivot, so it freely rotates around the pivot in the out-of-plane direction perpendicular to the floating surface.
The magnetic head supporting mechanism having the above mechanism has a roof portion formed by extending the tip of the flange portion of the load beam to the rear surface of the slider. Specifically, if the roof portion is projected onto the gimbal, its size is slightly smaller than or approximately equal to that of the gimbal. In addition, the roof portion is formed by integrally extending the flat portion of the flange portion, and is normally prevented from contacting the flexible finger portions and stage portion of the gimbal. That is, the roof portion does not restrain the movement of the slider.
According to this configuration, even when a large impact is applied to the magnetic-disc apparatus to cause the slider to jump from the disc surface and to start rotating around the pivot through a large angle, the gimbal, which rotates with the slider, contacts the roof portion to restrict the rotation of the slider. This enables the position (state) of the slider in which it contacts the disc surface after a jump to be controlled. Specifically, the substantial rotation of the slider causes the edges of the bleed surface of the slider (the four corners of the slider) or of the floating surface to contact the disc surface, thereby preventing the disc from being damaged due to a high contact area pressure (stress) caused by a small contact area.